117 lines
2.9 KiB
Python
117 lines
2.9 KiB
Python
import curses
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class Navigator(object):
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"""
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Handles cursor movement and screen paging.
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"""
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def __init__(
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self,
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valid_page_cb,
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page_index=0,
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cursor_index=0,
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inverted=False):
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self._page_cb = valid_page_cb
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self.page_index = page_index
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self.cursor_index = cursor_index
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self.inverted = inverted
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@property
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def step(self):
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return 1 if not self.inverted else -1
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@property
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def position(self):
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return (self.page_index, self.cursor_index, self.inverted)
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def move(self, direction, n_windows):
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"Move the cursor down (positive direction) or up (negative direction)"
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valid, redraw = True, False
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# TODO: add variable movement
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forward = ((direction*self.step) > 0)
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if forward:
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self.cursor_index += 1
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if self.cursor_index >= n_windows - 1:
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self.page_index += (self.step * self.cursor_index)
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self.cursor_index = 0
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self.inverted = not self.inverted
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redraw = True
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else:
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if self.cursor_index > 0:
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self.cursor_index -= 1
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else:
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if self._is_valid(self.page_index - self.step):
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self.page_index -= self.step
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redraw = True
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else:
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valid = False
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return valid, redraw
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def _is_valid(self, page_index):
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"Check if a page index will cause entries to fall outside valid range"
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try:
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self._page_cb(page_index)
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self._page_cb(page_index + self.step * self.cursor_index)
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except IndexError:
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return False
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else:
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return True
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class BaseViewer(object):
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"""
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Base terminal viewer incorperating a cursor to navigate content
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"""
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def __init__(self, content):
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self.content = content
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self.nav = Navigator(self.content.get)
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self._subwindows = None
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def draw_content(self):
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raise NotImplementedError
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def move_cursor_up(self):
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self._move_cursor(-1)
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def move_cursor_down(self):
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self._move_cursor(1)
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def add_cursor(self):
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curses.curs_set(2)
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self._edit_cursor(curses.A_REVERSE)
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def remove_cursor(self):
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curses.curs_set(0)
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self._edit_cursor(curses.A_NORMAL)
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def _move_cursor(self, direction):
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self.remove_cursor()
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valid, redraw = self.nav.move(direction, len(self._subwindows))
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if not valid:
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curses.flash()
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if redraw:
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self.draw_content()
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self.add_cursor()
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def _edit_cursor(self, attribute):
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window = self._subwindows[self.nav.cursor_index]
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n_rows, _ = window.getmaxyx()
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for row in xrange(n_rows):
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window.chgat(row, 0, 1, attribute)
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window.move(0, 0)
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window.refresh() |